Reversible airflow obstruction in lymphangioleiomyomatosis

Background: We previously reported that approximately one-fourth of patients with lymphangio-leiomyomatosis (LAM) may respond to therapy with bronchodilators. However, the validity of those observations has been questioned. The aims of the present study were to determine the prevalence of reversible airflow obstruction in patients with LAM and to identify associated clinical and physiologic parameters. Methods: First, the clinical and physiologic characteristics of 235 patients were analyzed to determine the frequency of the response to albuterol during a total of 2,307 visits. Second, we prospectively evaluated the response to albuterol (2.5 mg) and ipratropium (500 μg) in 130 patients, and correlated their responses with their clinical and physiologic characteristics. Results: In the retrospective study, 51% of the patients responded at least once to bronchodilators; of these, 12% responded ≥ 50% of the time. A higher frequency of positive bronchodilator responses was associated with greater rates of decline in FEV1 and diffusing capacity of the lung for carbon monoxide (DLCO). In the prospective study, 39 patients (30%) responded to bronchodilators, including 12 to ipratropium, 9 to albuterol, and 18 to both. The prevalence of asthma and smoking in the 39 responders was not different from that seen in the 91 nonresponders. Patients who responded to ipratropium, albuterol, or both had significantly (p < 0.02) lower FEV1 and DLCO, and a greater rate of FEV1 decline (p = 0.044) and DLCO decline (p = 0.039) than patients who did not respond to these bronchodilators. After adjusting for FEV1/FVC ratio, DLCO decline also was greater in responders than in nonresponders (p = 0.009). Conclusions: Patients with LAM may have partially reversible airflow obstruction. A positive response to bronchodilators is associated with an accelerated rate of decline in pulmonary function.